Street lighting luminaire



Jan. 3, 195o T, W.' ROLPH 2,493,087

STREET LIGHTING LUMINAIRE Filed Feb. 2, 1949 3 Sheets-Sheet 2 ,1l lllll ATTORNEY Jan. 3, 195o T w', RQLPH 2,493,087

STREET LIGHTING LUMINAIR Filed Feb. 2, 1949 5 srle's-sheex s INVENTOR 21m/ms h4 @LP/f ATTORNEY Patented Jan. 3, 1950 UNITED STATES PATENT OFFICE Holophane Company, Inc., New corporation of Delaware York, N. Y., a

Application February 2, 1949, Serial No. 74,139

l Claims.

The present invention relates to street lighting luminaires.

'I'he invention is more particularly directed toward street lighting luminaires each employing a single concentrated light source, a shielding reflector adapted to accept low angle light above the horizontal and reilect it across the vertical axis at angles too steep for effective street lighting at high ratios of spacing to mounting height, and a refractor to redirect said reflected light falling on it into higher angles whereby the spacing may be increased and to effectively utilize direct and reilected light at steep angles in lighting the nearer parts of the street or highway surface.

As shown in my prior Patent 2,260,693, a shielding reector alone cannot produce the desired high angled light, but by means of a suitable refractor high angled light may be obtained.

The present invention relates more especially to improvements in street lighting units of the general type shown in said patent.

According to the present invention not only is the high angled reilected light uniformly elevated by horizontal prisms in an upper tier so as to fall on remote street areas but other light, (relatively steep direct and reflected light falling in the lower regions of the refractor) is spread away from the nadir and elevated by horizontal prisms inlower tiers with downwardly decreasing refracting angles so that it merges with the dominant beam of reflected and refracted light. This improves the .lighted appearance of the refracting bowl notwithstanding its relatively greater vertical depth. The transition extends over so wide an area as to be less apparent. 'I'hls feature is suitable for all forms of street lighting units whether for symmetrical lighting or for mounting at the center of a street or crossing, or at the side of the street.

Where the invention is employed in asymmetric units, particularly in residential street lighting, relatively narrow sectors in the direction of the maximum beams may employ the horizontal prisms as. such light need not be deviated laterally. Light diverging more widely from the beam direction falls on sectors of the refractor laterally of the irst sectors and in these lateral sectors the invention contemplates the employment of diagonally disposed prisms which eiect both vertical and lateral deviation and reinforce the main beam. These diagonal 'prisms are preferably arranged in tiers of varying vertical and horizontal refracting angles.

The accompanying drawings show, for purposes of illustrating the present invention, several einbodiments in which the invention may take form, it being understood that the drawings are illustrative of the invention *rather than limiting the same.

In these drawings:

Figure 1 is a vertical sectional view through a luminaire of the symmetric type, showing paths of typical direct and,reected rays;

Figure 2 is a graph illustrating the relation of prism refracting power to angular position of the prism with respect to the nadir;

Figure 3 is a section of the symmetric refractor of Figure 1 and taken on line 3 3 thereof;

Figure 4 is a similar view of a refractor arranged for center of street mounting;

Figure 5 is a similar view illustrating a refractor arranged for mounting at a crossing;

Figure 5a is a diagrammatic view illustrating the generation of the diierent types of prisms employed in structures embodying the present invention;

Figure 6 is a top plan view illustrating in greater detail a refractor designed for side of street mounting;

Figure 7 is a perspective view looking into the refractor of Figure 6. in the direction oi the arrow 1, Figures 6 and '7;

Figure 8 illustrates a typical narrow asymmetric distribution obtained by a refractor such as shown in Figures 6 and '1; and

Figure 9 is a vertical section through a modiilcation.

The symmetrical unit illustrated in Figures l. 2 and 3 has an inverted, dome-shaped reflector I0 with steep walls and is concaved inwardly as shown. The portion of the reflector from its mouth II up to substantially the level indicated at I2 is preferably parabolic with downwardly sloping axis I3 intersecting the vertical axis |4- ll at I5 which is substantially on the same level as "the mouth II of the reflector. The upper part Illa of the reiiector is preferably spherical.

With a substantial point light source at I5.

y direct light rays between rays I6 and Il are re- Y l 3 such as Ila, Ila and Ila, cross the vertical axis and escape below the mouth of the reflector. The light source at I5 also emits direct light rays such as ray I8 directed toward the nadir and rays Il. 2l, 2| and 22 with increasing vertical angles.

The dominant light nux from the source emitted above the horizontal is in the reflected beam or parallel rays and the dominant light ilux below the horizontal is in the region below the horizontal of corresponding angular width. Ii the light nux in the parallel reflected beam were allowed to proceed directly toward a street or road surface, it would, as explained in my prior Patent- 2,260,693, -fall on the street at-distances so close to the luminaire as to require close spacing of the units. VIn order to permit wider spacing of the unitsjit is desirable to have the maximum higher than 67. The construction herein shown is one which elevates the dominant reilected light into angles of substantially 78 above the nadir.

iracting prisms. The prisms 29a, Illa send iight Vlight intensity emitted at angles substantially To obtain this elevated light it is necessary t0 y elevate such light through an angle oi 11.

In the construction herein shown the mouth of the reflector III isclosed'by a refracting bowl 2i. This bowl is of spherical contour with its center at 26 slightly above the light source l5. The general contour of the refractor form is obtained by rotating about the vertical axis ll-'II two concentric arcs centered at 26 and extending up nearly to the level of the mouth of the reilector. The outer surface of the refractor form may be considered for present purposes as smooth. It is usually, however, provided with a suitable diiiusion pattern. The inner surface of the retractor form for symmetrical lighting is provided with horizontal annular prisms. External prisms could be used if desired.

'Ihese horizontal prisms are arranged in tiers.

The uper tier 29 extending from the point 2`| down to the point 28 intercepts the parallel reected beam Ita, Ita, Ila, as well as the higher angle direct light rays. The prisms 30 from the point 2l to the nadir intercept direct light only. or light reflected from the upper spherical part lIlla of the reflector l0. The prisms 2S between points 21 and 28 are designed to have uniform light refracting power of 11 for the parallel rays. as indicated by the straight upper Aportion 3l of the graph shown in Figure 2. The prisms 30 from the point 28 to the nadir have uniformly decreasing refracting power for the direct light as indicated by sloping line l2 of the graph in Figure 2. This results in low brightness contrasts over the entire surface of the light refractor when viewed in the usual directions, and contrasts with previous designs wherein it is customary to provide a very short transition zone, as indicated by the dotted line 33 of the graph of Figure 2, and to omit prisms from the lower portion.

Figure 3 illustrates a plan view of a symmetric refractor containing prisms illustrated in detail in Figures 1 and 2. Such a refractor is suitable for use where symmetric lighting is desired.v

' The refractor shown in Figure 4 is designed for center of. street mounting. It has in plan a triangular sector with portions 29a and 30a occupied by prisms the same as prisms 29 and 3U in Figures l, 2 and 3. Such a zone, about 20 wide, elevates light received in radial vertical planes without eilecting lateral deviation and sends two strong beams of light in the street direction. laterally of the sectors 29a, 30a the refractor oi' Figure 4 in the direction of the arrow 3l. Diagonal prisms in regions 3.5 elevate light falling on them and deviate in directions 36 substantially parallel with l1. The laterally reiracting prisms 36 tend to keep the light away from the sides of the street and generally direct it lengthwise of the street as indicated at arrow `I9. y

The refractor 40 of mounting on the center oi' an intersection. It has tiers oi prisms 29a, 30a as before and diagonal prisms 36, as above discussed, and is adapted for producing iour'beams of light at right angles to one another as indicated by the arrows 4i.

A corresponding refractor form is diagrammatically illustrated in light full lines in Figure 5a. It may be compared with the southern hemisphere oi the globe, omitting, a portion near the equator. It is apparent that such a spherical object, i. e., the spherical surface of the plunger to be used in forming the pressed glass refractor, could be provided with ribbings similar to parallels of latitude suitable to form horizontal prisms by turning the mold about a vertical axis A, A and cutting horizontal lines such as indicated at a. These will correspond with the parts of the mold necessary in making the horizontal prisms 29 yand 30. II the plunger is turned about a horizontal or equatorial axis B, B, one could obtain radial or vertical prisms meridianally disposed as indicated by the line'b. These correspond with the prisms 36 of Figure 4.

Any plane passing through the center of a sphere forms a great circle on the surface oi the sphere and such an oblique plane is indicated at C. A plane parallel with C would intercept the sphere in a diagonal or oblique line such as indicated at c. Suitable contours can therefore be made on a spherical mold to provide diagonal elements as c by turning the mold on an axis at right angles to the great circle C. In such manner each of the prism elements in area 35 of Figures 4 and 5 can be provided for by properly cutting the face of the plunger.

The refractor shown in Figures 6 and 7 is designed for side of street mounting to produce narrow asymmetric distributions of I. E. S. type II. Such distributions have a lateral width in the neighborhood of 20-25, a maximum candle power in the region of above the nadir and distribute light generally over the entire width .of the street alongside which they are mounted.

With the 75 angle of maximum beam, the ratio of spacing to the mounting height may be 8 to 1.

The vertical axis of the refractor of Figures 6 and 7 is indicated at the point 60. The house side of the refractor is at the top of the gurc and the street side at the bottom of the figure, and the refractor is designed to produce strong beams of light generally in directions E and W which are, in the example shown, 10 below the horizontal line BI-BI parallel with the curb. The right and left sides of the refractor as viewed in Figure 6 are alike, the vertical line 62-62 representing a plane of symmetry, and an orientation notch $3 is placed in the refractor as indicated.

As the refractor is symmetrical on opposite sides of the line 62-62, the structure at one side of this line will be described and the same reference characters used for the other side. An upper tier of prisms l0 is disposed adjacent the vertical has areas 35, t5 carrying diagonal prisms ,and 75 radial plane in the beam direction E. This tier Figure 5 is 4arranged for' of horizontal prisms 1I corresponds with the horizontal prisms 29 of Figure 1. It serves to collect light diverging through an ansie of about 20 in horizontal planes and between substantially 38 from the nadir and 75 from the nadir and transmits it at higher angles without lateral deviation. This light falls upon the entire width of the street in the region midway between adjacent street lighting luminaires. Below the tier of prisms and closer to the median plane 62-52, the refractor has a tier of horizontal prisms 1I which have refracting values corresponding with the upper prisms in the region 3l of Figure 1. These prisms serve to transmit the direct light received below the prisms in tier 1I toward intermediate street areas and are placed farther from the axis BI--GI than the tier 10 so as to cover the street width closer to the luminaire.

At still lower levels on the refractor and extending between the vertical axis 62-62 of the gure and region 1|, the refractor has a lower tier of prisms 12 of still less refracting power corresponding to the lower portion of the line 32 on the graph of Figure 2. These prisms of comparatively low refracting power are generally parallel but as shown in Figure 6 of the drawings converge toward the street side so as to assist in spreading the nearly vertical light generally in the direction of the street area.

On the house side of the tier of prisms represented at 10, 1| and 12, the refractor has three tiers of diagonal prisms, namely, an upper tier 13, an intermediate tier 1I, and a lower tier 15. These tiers extend over to a radial line 64. Each of the prisms in the upper tier 13 is oblique to the incident light and effects both elevation of this light and lateral redirection. The prisms in region 13 have the same vertical light elevating power as those in sector 10, and have increasing lateral deviating power. The prisms in region 14 appear in plan to be continuations of the prisms 13. They are, however, made to have less refracting power in vertical planes and somewhat less maximum refracting power laterally than the corresponding prisms in the upper tier. The prisms 15 in the lower tier receive rather steep direct light and have still less vertical refracting power but substantially the same laterally refracting power as the prisms in region 1I. The diagonal prisms in regions 13. 14 and 15 converge upwardly toward one another.

On the street side, the refractor is provided with an upper tier of prisms 16, optically similar to the upper tier of prisms 13 but with reverse sign. These extend over to the line l5 which may be the same angular distance from 9| as is line 64. The street side of the refractor also has a tier of diagonal prisms 11 similar to the prisms 14 but of reverse sign. These extend nearly to the vertical axis 62-62.

The house side of the refractor has a series of laterally deviating prisms 1I occupying the area from the line 64 to the vertical axis Il and designed to laterally deviate the direct light and generally shift it into the direction of the beam. The prisms 18 become too small near the center of the bowl and terminate as indicated. The street side of the refractor has vertical laterally deviating prisms 19 occupying the area between the line 65 and line 92 and down to the diagonal prisms 11.

While the diagonal prisms in regions such as 13, 14, 15, 16 and 11 appear in the drawing to be curved, each prism lies in a plane and when viewed in that plane appears straight, as shown' by the bold line Il of Figure '7.

The following table indicates refracting powers for prisms in the various areas discussed.

Vertical Lateral Regio Action Action Degrees Degrees 70 l1 7l 7li 0 'I2 0-75 0 73 il 10-40 76 ll l0-40 74 9 12-32 77 9 12-32 75 3% 12-32 The output of the refractor of Figures-6 and 'I is illustrated in Figure 8.` Here the circle illustrates the symmetric distribution in horizontal planes from a bare lamp and the photometric curve 9| illustrates the asymmetric distribution in vertical planes through the cone of maximum candle power, which in the present instance is about 78 above the nadir.

Figure 9 illustrates a luminaire having a deep shielding reector 92 adapted to produce downwardly sloping rays 93 from a light source 94. These rays, as well as direct rays 95, are intercepted by a refracting bowl 86 having prism systems similar to those above described. The refracting powers will depend upon the vertical angles of the rays received and the vertical angle of the light to be omitted and the radius of curvature of the elemental area of the bowl in which they are placed. In the figure the upper horizontal prisms of uniform refracting power are indicated at 91, the horizontal prisms of decreasing refracting power to nadir at 99, and diagonal prisms at 99.

The dominant light output from the luminaires comes from the upper portions of the refractors and hence it is possible without affecting the dominant light output to employ in regions below the portion of the refractor acting on the dom: inantly reflected beam diierent contours and prismatic constructions from those specifically shown.

Since it is obvious that the invention may be embodied in other forms and constructions within the scope of the claims, I wish it to be understood that the particular form shown is but one of these forms, and various modiilcations and changes being possible, I do not otherwise limit myself in any way with respect thereto.

1. A luminaire comprising a substantially point light source, a reflector form having comparatively steep walls disposed about a vertical axis and concave in all directions toward the light source and intercepting a band of light extending upwardly from the horizontal plane through the light source and reilecting it across the reflector axis and out through the mouth of the reflector at a predetermined vertical angle, and a refracting bowlbelow the reflector form and of a depth to intercept the reflected light after it has cross the reflector axis, the refracting bowl being of substantially spherical contour below the mouth of the reector and'having, near the top thereof and adjacent to a radial vertical median plane, prism systems for concentrating an intercepted band of reflected light of substantial angular width on both sides of said of horizontal light elevating prisms of uniform refracting power and substantially of .said narrow angular width, and laterally of said horizontal prisms upwardly andoutwardly diverging, diagonally located prisms whose refracting power in vertical planes is substantially the same as that of the horizontal prisms and whose refracting power in horizontal planes increases as they become more remote from the series of horizontal prisms whereby reflected light falling on the diagonal prisms is correspondingly elevated and laterally deflected toward the light emitted through the horizontal prisms.

2. A luminaire such as claimed in claim 1, wherein the diagonally located prisms on each side converge upwardly.

3. A luminaire such as claimed in claim 1, having similar prism systems adjacent to a second radial plane and vertical, laterally refracting prisms adjacent the outermost diagonal prisms for intercepting the more diverging reected light and refracting it generally toward sa radial planes.

4. A luminaire such as claimed in claim 1, wherein the refractor intercepts direct light below the reflected light and has below the horizontal prisms of uniform refractlng power additional prisms generally parallel therewith and of refracting power decreasing from said power to zero in the regions of a nadir for divergently spreading direct light from the nadir up to the reflected light refracted by said rst mentioned A horizontal prisms. e

5. A luminaire such as claimed in claim, l, wherein the refractor intercepts direct light below the reected light and has below the horizontal prisms of uniform refracting power addtional prisms generally parallel therewith and of refracting power decreasing from said power to zero in the region of the nadir for divergently spreading direct light from the nadir up to the reflected light refracted by said rst mentioned horizontal prisms, and has similar diagonal prisms laterally of said additional prisms which intercept more horizontally divergent direct light, elevate it and refract it toward said` radial plane.

6. A luminaire such as claimed in claim 1, having similar prism systems adjacent a second radial plane and vertical. laterally refracting prisms adjacent the outermost diagonal prisms for intercepting the more diverging reflected light and refracting it generally toward said radial planes, wherein the refractor intercepts direct light below the reflected light and has below the horizontal prisms of uniform refracting power additional prisms generally parallel therewith and of refracting power decreasing from said power to zero in the regions of the nadir for divergently spreading direct light from the nadir up to the reected light refracted by said irst mentioned horizontal prisms.

7. A luminaire comprising a light source, a reflecter of substantially parabolic prole with the focus at the light source with the axis down wardly sloping and intercepting a band of light extending above the horizontal plane through the light source and reilecting it at substantially uniform downwardly sloping angles parallel with the axis across the reflector axis and out through the mouth of the reflector, and a prismatic refracting bowl of the same outside diameter as the mouth of the reflector and occupying a vertical angle of substantially above the nadir. the refractor having a spherical portion provided with a series of horizontal prisms of uniform refracting power to accept the parallel reflected rays and elevate them uniformly into higher angles and between said horizontal prisms of uniform refracting power and nadir an inwardly concave portion which is provided with a series of light spreading prisms extending to the nadir and having refracting powers which decrease from said refracting power to zero in the region of the nadir.

8. A luminaire such as claimed in claim '1, wherein said horizontal prisms and spreading prisms occupy narrow horizontal angles and the refractor has laterally thereof diagonal prisms which eiect vertical elevation and lateral deviation of reflected light falling thereon, the vertical refracting power being substantially equal to that of the horizontal prisms and the lateral refracting power increasing as the diagonal prisms become more remote from the horizontal prisms.

9. A prismatic refracting bowl of inwardly concave contour and occupying substantially 75 above the nadir in all azimuths, the bowl having a series of horizontal prisms occupying a vertical angle of substantially 38 and uniform refracting power to elevate parallel downwardly sloping rays in radial vertical planes into higher angles while maintaining parallelism and between the horizontal prisms and the nadir a series of prisms whose refracting power decreases from that of the irst mentioned prisms to zero so as to spread light radiating from regions adjacent the center of curvature of the bowl up to the higher angled retracted light.

10. A prismatic refracting bowl of inwardly concave contour and occupying substantially 75 above the nadir in all azimuths, the refracting bowl having in two generally opposite azimuthal directions a series of horizontal prisms near the periphery and of limited angular length and of uniform light elevating refracting power for deviating downwardly sloping parallel rays crossing the axis and falling on the upper inside of the bowl in radial vertical planes into higher vertical angles without change of azimuthal direction, and below said rst mentioned horizontal prisms additional horizontal prisms generally parallel therewith and with refracting power which decreases from said uniform refracting power to zero for spreading light radiating from regions adjacent the center of curvature of the bowl from the nadir up to the higher angled retracted light.

11. A refracting bowl such as claimed in claim l0 having laterally of the rst mentioned horizontal prisms an area occupied by oblique prisms with their active surfaces sloping away from the horizontal prisms at variant angles such that for similar downwardly sloping parallel light falling on said areas, the latter light is elevated to substantially the same extent as that by the horizontal prisms and is laterally relracted toward the horizontally divergent beam emitted by said horizontal prisms.

12. A refracting bowl as claimed in claim 10 having laterally of the ilrst mentioned horizontal prisms an area occupied by oblique prisms with their active surfaces sloping away from the hori- 75 zontal prisms at variant angles such that for similar downwardly sloping parallel light falling on said areas, the latter light is elevated to substantially the same extent as that by the horizontal prisms and is laterally refracted toward the horizontally divergent beam emitted by said horizontal prisms, the bowl also having laterally of the oblique prisms vertical laterally refracting prisms extending midway between the azimuthal planes.

13. A refracting bowl of generally uniform thickness and having opposed surfaces generated by the rotation about a vertical axis of opposed upwardly concave curves extending upwardly from nadir, one surface having sectors of substantial angular extent about said vertical axis occupied by horizontal prismatic ribs thicker at the top than at the bottom for elevating light falling thereon in vertical radial planes without deviating it out of said planes, and adjacent said regions of horizontal prisms sectors occupied by diagonally disposed prisma'tic ribs diverging upwardly and outwardly and thicker toward the horizontal prisms for elevating light falling thereon in radial vertical planes and laterally deviating it toward the light emitted by the horizontal prismatic ribs.

14. A refracting bowl such as claimed in claim 13, wherein the horizontal and diagonal prismatic ribs are arranged in vertical tiers. all the ribs in 10 the upper tier having a uniform vertical refracting angle and those in the lower tiers having progressively lessening vertical refracting angles.

15. A refracting bowl of generally uniform thickness and having opposed surfaces generated by the rotation about a vertical axis of opposed upwardly concave curves extending upwardly from the nadir, certain sectors being occupied by horizontal light elevating prisms which eifect no lateral deviation of outwardly proceeding light in vertical radial planes, and sectors adjacent thereto and occupied by prisms cut on lesser circles parallel with obliquely disposed greater circles for eiecting both vertical and lateral deviation of outwardly proceeding light in radially vertical planes.

THOMAS W. ROLPH.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,597,185 Dorey Aug. 24, 1926 1,731,714 Dorey Oct. 15, 1929 2,260,693 Rolph Oct. 28, 1941 2,474,326 Rolph June 28. 1949 

